The present invention relates to thermostats, and more particularly to a temperature responsive, fluid control valve for pneumatic control systems that performs multiple control functions.
Thermostats for pneumatic control systems are generally of the type that have a temperature responsive expansible element connected to a valve that opens or closes a port to either apply pressurized control fluid to an element to be operated or to bleed pressurized control fluid from that element. It is a broad object of the present invention to provide an improved thermostat for pneumatic control systems that can perform multiple control functions upon a single throw of a temperature responsive expansible element. More particularly, it is an object of the present invention to provide a thermostat for a pneumatic control system that can vary control pressure to two or more elements to be controlled, simultaneously or sequentially, inversely or directly proportional to a temperature change, and, linearly or nonlinearly with respect to a change in temperature.